A modulated Faraday rotation signal is produced by passing a linearly polarized laser beam through a semiconductor wafer sample in a modulated magnetic field that is induced in an electromagnet by a sine wave generator and driver coupled thereto. The rotation signal is normalized by dividing by a transmission signal produced by modulating the beam with a chopper that operates at a different frequency from the frequency of the driver. The result is a Faraday rotation measurement with high signal-to-noise ratio and compensation for laser drift in intensity.
申请公布号
US5210417(A)
申请公布日期
1993.05.11
申请号
US19920839627
申请日期
1992.02.24
申请人
THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE ARMY
发明人
GRISHAM, JOHN A.;CLARKE, FREDERICK W.;CHRISTENSEN, CHARLES R.;STENSBY, JOHN L.